1. Field of the Invention
The present invention is directed to management, testing and maintenance of cellular telephone systems. More particularly, the present invention is directed to a system and method for (i) remotely monitoring the call parameters of a mobile cellular telephone call and (ii) displaying those parameters in a dynamic graphical form in real or near real time, wherein the graphical form also includes the mobile cellular telephone's location.
2. Background of the Invention
Unfettered mobile telephone network access, call continuity and call clarity are some of the technical considerations that are continually optimized to achieve a high level of mobile cellular telephone service. To achieve improved performance levels, cellular telephone service providers must position antennas in geographically desirable locations and tune and/or direct the antennas in optimal ways. While radio frequency (RF) engineering tools exist to help properly position individual cellular telephone cell site antennas and configure overall cellular systems, the only effective way of actually determining whether the cellular antennas and their tuning/positioning have been properly accomplished is to perform field tests with a cellular telephone. Typically, such field tests are accomplished with “drive tests” wherein an RF or cellular engineer drives a vehicle around in a designated area while making one or more telephone calls using his mobile cellular telephone. During the drive test, the RF engineer monitors call performance by noting call drops, for example, and/or collecting actual downlink data such as signal strength directly from the mobile telephone. Test equipment for performing such tests is manufactured by, for example, X-Tel, Comarco and LCC.
The RF engineer then returns to his office where he uploads the collected data to, e.g., a computer spreadsheet program, and attempts to combine or correlate this data with data, from the same time period as the drive test, obtained from the cellular system's controller or switch, i.e., a Mobile Telephone Switching Office (MTSO) or Mobile Switching Center (MSC). The data from the switch might include signal strength, Bit Error Rate (BER) and other call events, such as call handoffs, during the time that the RF engineer was performing the drive test.
Once an analysis of the combined data is complete and changes to the cellular system are made (if necessary), the RF engineer will typically return to the drive test area to confirm that the changes made have improved overall system performance. The iterative procedure of drive testing, system changing, and subsequent drive test confirmation continues as long as cellular system subscribers (users) complain about inadequate service or it is believed that improved service, e.g., coverage and continuity, can be achieved.
While the drive test is an effective method for confirming and testing system performance, it is also an extremely inefficient exercise, in terms of time, for an RF engineer. Instead of spending valuable time making calculations and studying data to optimize a cellular system in an office setting, the RF engineer might spend half or even up to two thirds of his day driving to, around and from an area under investigation. This drive test time factor is even more pronounced if the RF engineer must travel to a rural area to investigate customer complaints and/or perform routine system checks. Thus, the drive testing conventionally employed to monitor and upgrade a cellular system's performance wastes an RF engineer's valuable time.
Moreover, even if the data collected by the RF engineer and the switch data are combined in a useful manner for analysis, it is very difficult to ascertain from the foregoing data set the actual location of the mobile telephone at any given time. Such information, however, can be critical to determine precisely where the cellular system has inadequate service. That is, it is important to know, for example, the precise geographical location at which a call drop occurs. However, having only data collected from the mobile telephone and data from the switch cannot provide accurate position location information.
Additionally, the data that is collected from the mobile telephone and switch is often rather “cryptic.” Specifically, while individual parameters such as signal strength, BER, etc. are recorded over time by the switch (and where possible, by the mobile telephone itself), these parameters are output from the switch (and/or mobile telephone) as numeric or text data, which is difficult to understand unless one has extensive knowledge of the various codes and formats employed. FIG. 1 shows a typical “feed” of data from a switch. This intelligibility difficulty is compounded by the fact that cellular system providers often deploy switches from different manufactures, e.g., Hughes, Lucent or Ericsson, and each of these manufacturers provides call information data in different formats and in different orders. This makes it particularly difficult to fully appreciate the data that is available, let alone to properly correlate the call information data from the switch with the mobile telephone data, if any, for analysis.